1. Field of the Invention
The present invention relates to a gas flow direct pressure regulator, and more particularly to an improvement to a direct pressure regulator which can regulate the flow of gas responsive to the gas pressure.
2. Description of Prior Art
It is known to the person skilled in the art that in a central gas supply system the gas flow gets lower and lower as the gas approaches the terminal of the piping. At peak utilization hours, as at dinner hours, the gas flow at the terminal is particularly low. In conventional gas flow regulators, the gas passage is mostly provided in such a zigzag way that the pressure difference between the inlet and the outlet of the gas flow regulator is large. In low-pressure gas supply systems, which has a gas pressure as low as 0.01kg/cm.sup.2, the gas pressure at the terminal is low enough to cause an insufficient supply of gas to the user. In winter days, this would cause the heating capacity to be very low.
To cope the aforementioned problem, the inventor has proposed a gas flow regulator disclosed in UK Patent Application GB 2,233,068A entitled "A Direct Pressure Regulator Which is Responsive to Fluid Pressure". The patent can solve the problem of insufficient gas supply in winter days. The structure of the prior art regulator is shown in FIGS. 1 and 2.
There are found several drawbacks of the prior art regulator that, as shown in FIG. 2, the bottom chamber is in direct communication with the top chamber and each of which is air-tight separated. In factory, such a structure arrangement causes two constituent parts of the timer device, namely the cam and the main shaft, not to be able to be assembled beforehand and the work has to be done after the assembly of the timer device on the regulator is completed. Working hours for the labor in making the assembly is thus time-consuming. Moreover, if the timer device fails or is under maintenance so that it must be replaced, the technician must shut off the gas supply first and then remove the screws 33, washer 32, and cam 31 (shown in FIG. 1) and then the bottom cover (not shown) on the top chamber and the mounting plate 48 for the timer device before the timer device can be removed. The work, as anybody can realize, is quite laborious and time-consuming. After replacement for the timer device is completed, the cutaway portion 310 of the cam 31 on the timer device must be precisely aligned with the swinging arm 21, and after that, adjust the two components in specific orientations. This work is also laborious and time-consuming.
In addition to the foregoing drawbacks, the prior art regulator, as shown in FIG. 1, is composed of at least 27 various components. The assembly work is thus time-consuming. In particular, the assembly of the valve bar 13 and the valve piece 11 must employ high-end technology. In that, the valve bar 13 is formed by machining a copper bar and then handed to the injection molding plant, where specialized personnel operates the injection molding to integrally form the valve bar 13 with the valve piece 11. This procedure is necessary because the valve piece 11 is formed with a protruded member 110 and slits 111 and the valve bar 13 has its end formed with grooves for coupling with an E-type buckling ring 16 so that the two components can not be easily integrally formed with plastics. To do it, the cost for the molds is extremely high.